firefox-main/xpcom/string/nsUTF8Utils.h (file symbol)

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsUTF8Utils_h_
#define nsUTF8Utils_h_
// NB: This code may be used from non-XPCOM code, in particular, the
// standalone updater executable. That is, this file may be used in
// two ways: if MOZILLA_INTERNAL_API is defined, this file will
// provide signatures for the Mozilla abstract string types. It will
// use XPCOM assertion/debugging macros, etc.
#include <type_traits>
#include "mozilla/Assertions.h"
#include "nsCharTraits.h"
#ifdef MOZILLA_INTERNAL_API
# define UTF8UTILS_WARNING(msg) NS_WARNING(msg)
#else
# define UTF8UTILS_WARNING(msg)
#endif
class UTF8traits {
public:
static bool isASCII(char aChar) { return (aChar & 0x80) == 0x00; }
static bool isInSeq(char aChar) { return (aChar & 0xC0) == 0x80; }
static bool is2byte(char aChar) { return (aChar & 0xE0) == 0xC0; }
static bool is3byte(char aChar) { return (aChar & 0xF0) == 0xE0; }
static bool is4byte(char aChar) { return (aChar & 0xF8) == 0xF0; }
static bool is5byte(char aChar) { return (aChar & 0xFC) == 0xF8; }
static bool is6byte(char aChar) { return (aChar & 0xFE) == 0xFC; }
// return the number of bytes in a sequence beginning with aChar
static int bytes(char aChar) {
if (isASCII(aChar)) {
return 1;
}
if (is2byte(aChar)) {
return 2;
}
if (is3byte(aChar)) {
return 3;
}
if (is4byte(aChar)) {
return 4;
}
MOZ_ASSERT_UNREACHABLE("should not be used for in-sequence characters");
return 1;
}
};
template <typename Char, typename UnsignedT>
inline UnsignedT RewindToPriorUTF8Codepoint(const Char* utf8Chars,
UnsignedT index) {
static_assert(std::is_same_v<Char, char> ||
std::is_same_v<Char, unsigned char> ||
std::is_same_v<Char, signed char>,
"UTF-8 data must be in 8-bit units");
static_assert(std::is_unsigned_v<UnsignedT>, "index type must be unsigned");
while (index > 0 && (utf8Chars[index] & 0xC0) == 0x80) --index;
return index;
}
#undef UTF8UTILS_WARNING
#endif /* !defined(nsUTF8Utils_h_) */